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Applied and Environmental Microbiology, December 2005, p. 8091-8098, Vol. 71, No. 12
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.12.8091-8098.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Compatible Solutes of the Hyperthermophile Palaeococcus ferrophilus: Osmoadaptation and Thermoadaptation in the Order Thermococcales

Clélia Neves,1* Milton S. da Costa,2 and Helena Santos1*

Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2780-156 Oeiras, Portugal,1 Departamento de Bioquímica and Centro de Neurociências de Coimbra e Biologia Celular, Universidade de Coimbra, 3004-517 Coimbra, Portugal2

Received 26 July 2005/ Accepted 12 September 2005

The effect of salinity and growth temperature on the accumulation of intracellular organic solutes was examined in the hyperthermophilic archaeon Palaeococcus ferrophilus. The genus Palaeococcus represents a deep-branching lineage of the order Thermococcales, which diverged before Thermococcus and Pyrococcus. Palaeococcus ferrophilus accumulated mannosylglycerate, glutamate, and aspartate as major compatible solutes. Unlike members of the genera Pyrococcus and Thermococcus, Palaeococcus ferrophilus did not accumulate di-myo-inositol phosphate, a canonical solute of hyperthermophiles. The level of mannosylglycerate increased in response to both heat and salt stress; glutamate increased at supraoptimal growth temperatures, whereas aspartate increased at supraoptimal salt concentration. Proline, alanine, and trehalose were also found in lesser amounts, but their levels did not respond significantly to any of the stresses imposed. Additionally, the genes involved in the synthesis of mannosylglycerate in Palaeococcus ferrophilus and Thermococcus litoralis were identified. In both organisms the synthesis proceeds via the two-step pathway comprising mannosyl-3-phosphoglycerate synthase (MPGS) (EC 2.4.1.217) and mannosyl-3-phosphoglycerate phosphatase (MPGP) (EC 3.1.3.70). The mpgS and mpgP genes of Palaeococcus ferrophilus were expressed in Escherichia coli and the proteins were characterized. MPGS had maximal activity at 90°C and pH near 7.0, and was strictly dependent on Mg2+. MPGP had optimal activity at 90°C and pH 6.0 and was barely dependent on Mg2+. The half-life values for inactivation of MPGS and MPGP at 83°C were 18 and 25 min, respectively. A comparative discussion of the osmo- and thermoadaptation strategies in these three genera of the Thermococcales is presented.

* Corresponding author. Mailing address: Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Rua da Quinta Grande 6, Apartado 127, 2780-156 Oeiras, Portugal. Phone: 351-214469800. Fax: 351-214428766. E-mail: santos{at}itqb.unl.pt.

Applied and Environmental Microbiology, December 2005, p. 8091-8098, Vol. 71, No. 12
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.12.8091-8098.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Rodionov, D. A., Kurnasov, O. V., Stec, B., Wang, Y., Roberts, M. F., Osterman, A. L. (2007). Genomic identification and in vitro reconstitution of a complete biosynthetic pathway for the osmolyte di-myo-inositol-phosphate. Proc. Natl. Acad. Sci. USA 104: 4279-4284 [Abstract] [Full Text]  
  • Lamosa, P., Goncalves, L. G., Rodrigues, M. V., Martins, L. O., Raven, N. D. H., Santos, H. (2006). Occurrence of 1-Glyceryl-1-myo-Inosityl Phosphate in Hyperthermophiles. Appl. Environ. Microbiol. 72: 6169-6173 [Abstract] [Full Text]  


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